I was thinking about fighters going into say the Middleweight division, and weighing in at 180 - 181, would that be a bad move? Would have the fighter been better off just cutting the weight to 170?

I know there are certain factors to considor when making a weight class and going in as heavy as possible, but suppose your body was just in the balance of those 2 class' and there was someone you wanted to fight at the higher class but also didnt want to pack on too much fat, or just really wanted to compete at that level, would making the weight 5 or 6 lbs light be a bad thing?